Electrical plug with anti-shock prongs



March 3, 1964 A. J. WILLIAMS.

ELECTRICAL PLUG WITH ANTI-SHOCK PRONGS Filed Feb. 29, 1960 4 lNvEyTolg. g my ,2 WILL/A Ms 4 Tmmsy;

United States Patent Ofiice 3,123,424 Patented Mar. '3, 1964 3,123,424 ELECTRICAL PLUG WITH ANTI-SHOCK PRONGS Arthur J. Williams, 942 University Place, Grosse Pointe 30, Mich. Filed Feb. 29, 1960, Ser. No. 11,756 2 Claims. (Cl. 339-195) This invention relates generally to improvements in electrical connecting male plugs for domestic applications and the like, and more particularly to a novel and improved male connecting plug incorporating insulated contact prongs for the prevention of shocks when the user accidently contacts the prongs during insertion of the plug into or withdrawing the plug from a mating wall outlet receptacle or the like.

It is the primary object of the present invention to provide a male electrical plug for common household use and the like which is provided with insulated contact prongs which may be grasped by the user to guide the prongs into a mating plug receptacle without danger of causing a short circuit condition through the fingers and body of the user, but permitting the prong outer ends to make efficient metallic contact with the mating plug receptacle.

It is another object of the present invention to provide an electrical male plug having insulated prongs and which is simple and compact in construction, economical of manufacture and efficient in operation.

It is a further object of the present invention to provide an electrical male plug which is provided with insulated contact prongs and wherein the prongs may be selectively provided with exposed contact making portions on the outer ends thereof on either the inner sides thereof or on both the inner and outer sides thereof as desired.

Other objects, features and advantages of this invention will be apparent from the following detailed description and appended claims, reference being had to the accompanying drawing forming a part of the specification wherein like reference numerals designate corresponding parts of the several views.

In the drawing:

FIG. 1 is a top plan view of an electrical male plug made in accordance with the principles of the invention;

FIG. 2 is a fragmentary elevational view of the structure in FIG. 1, taken along the line 2-2 thereof and looking in the direction of the arrows;

FIG. 3 is a fragmentary perspective view of one of the insulated prongs employed in the invention;

FIG. 4 is an elevational sectional view of the structure shown in FIG. 2, taken along the line 4-4 thereof and looking in the direction of the arrows;

FIG. 5 is an end elevational view of the structure illustrated in FIG. 1, taken along the line 5-5 thereof and looking in the direction of the arrows;

FIG. 6 is a fragmentary top plan view of a modified male electrical plug made in accordance with the principles of the invention; and,

FIG. 7 is an elevational sectional view of the structure illustrated in FIG. 6, taken along the line 7-7 thereof and looking in the direction of the arrows.

Referring now to the drawing, and in particular to FIGS. 1 through 5, the numeral 16 indicates the base element of a male electrical plug which is adapted to receive the usual two wire electrical cord 11. The numerals 12 and 13 generally indicate a pair of insulated contact prongs which have their inner ends fixedly mounted in the plug base element 10 by any conventional or usual methods, and which are connected in the usual manner to the conductive wires of the cord 11. Although two contact prongs 12 and 13 are shown in the illustrative embodiment, it will be obvious that three such prongs could be employed, if a three phase electrical male plug or the like is desired.

The contact prongs 12 and 13 are both constructed in the same manner and, accordingly, only one prong will be described in detail. As shown in FIGS. 1 through 4, the contact prong 12 includes the metal conductor strip or arm 14 which is covered on all sides thereof with a layer of any suitable insulation such as a plastic material, Bakelite or the like. It will be seen that the insulation material extends over the top, bottom, inner and outer sides of the prong as well as the outer end thereof. The outer end of the metal arm or center portion of the prong is substantially T-shaped in cross section with the leg of the T projecting outwardly from the insulation to form the exposed metal contact area or portion. The head of the T-shaped contact area is formed by the metal arm 14. The contact portion 16 projects sidewardly inwardly from the metal arm 14 as shown in FIG. 1. The insulation material 15 may be of any suitable thickness and is preferably of a thickness corresponding to the size of the metal arm 14 whereby the overall size of these two parts when combined is equal to the standard or usual overall size of conventional plug prongs. The exposed contact portion 16 preferably extends approximately .006 of an inch beyond the inner side of the insulation material 15. The thickness and size of the aforementioned prong parts are exaggerated in the drawing for illustration purposes.

In use, the electrical plug of the present invention is adapted to be inserted into a conventional wall outlet receptacle or the like in the usual manner. In the usual wall plug the metal contact areas are so disposed whereby they will make electrical contact with the exposed contact portions 16 when the plug is inserted in the outlet receptacle. It will be seen that the user may touch the sides and ends of the prongs 12 and 13 without danger of creating a short circuit through the fingers and body of the user with a resultant electrical shock.

FIGS. 6 and 7 illustrate another modification of the invention. In this second embodiment the base element is indicated by the numeral 10a and the prongs by the numerals 12a and 13a. The prongs 12a and 13a are provided with the inwardly directed contact portions 16 and also with the outwardly directed contact portions 16a. It will be seen that the plug shown in FIGS. 6 and 7 may be used with mating outlet receptacles which have metal contact members for engaging either the inner or outer sides of a male plug.

It will be seen that the male electrical plug of the present invention provides a plug of this type which is compact and simple in construction and which provides optimum safety to the user. While it will be apparent that the preferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What I claim is:

1. In an electrical male plug, the combination of: a base element having at least a pair of contact prongs extended outwardly from one end thereof; each of said prongs including an elongated central conductive member; said central conductive member being completely covered on its top and bottom sides, and outer end, and completely covered on the inner and outer sides except for contact areas, with an insulating material; and, an exposed contact means extended sidewardly inwardly from said central conductive member and through said insulating material at said contact areas for making electrical contact with a contact means in a mating electrical female re ceptacle.

2. In an electrical male plug, the combination of: a

3 A base element having at least a pair of contact prongs for making electrical contact with a contact means in a extended outwardly from one end thereof; each of said mating electrical female receptacle. prongs including an elongated central conductive mem- Refemmgs Cited in the mg of this Patent oer; said central conductive member being completely covered on its top and bottom sides, and outer end, and UNITED ATE AT NT completely covered on the inner and outer sides except 1 21 3 4 (goodridge Mar 15 19 7 for contact areas, with an insulating material; and, an 2537379 Farms J 9 195 exposed contact means extended sidewardly both inwardly and outwardly from said central conductive member FOREIGN PATENTS and through said insulating material at said contact areas 10 583,285 Great Britain Dec. 13, 1946 

1. IN AN ELECTRICAL MALE PLUG, THE COMBINATION OF: A BASE ELEMENT HAVING AT LEAST A PAIR OF CONTACT PRONGS EXTENDED OUTWARDLY FROM ONE END THEREOF; EACH OF SAID PRONGS INCLUDING AN ELONGATED CENTRAL CONDUCTIVE MEMBER; SAID CENTRAL CONDUCTIVE MEMBER BEING COMPLETELY COVERED ON ITS TOP AND BOTTOM SIDES, AND OUTER END, AND COMPLETELY COVERED ON THE INNER AND OUTER SIDES EXCEPT FOR CONTACT AREAS, WITH AN INSULATING MATERIAL; AND, AN EXPOSED CONTACT MEANS EXTENDED SIDEWARDLY INWARDLY FROM SAID CENTRAL CONDUCTIVE MEMBER AND THROUGH SAID INSULATING MATERIAL AT SAID CONTACT AREAS FOR MAKING ELECTRICAL CONTACT WITH A CONTACT MEANS IN A MATING ELECTRICAL FEMALE RECEPTACLE. 